This invention relates to the technical field of oil production, more specifically, to a method and a machinery system of mechanical oil production with a sucker-rod pump.
During production of oil well with a rod pump, the expense of energy consumption forms a large part of the variable cost with the price of electricity increasing, its proportion has been more than 12%. The average efficiency of machinery system of oil production is an important index, which represents the level of mechanical oil production, and in xe2x80x9cEighth five year planxe2x80x9d period of our country the average efficiency was 24%. This means a large amount of energy wasted in lifting process. If the efficiency of the machinery system of oil production is increased from 20.4% to 30%, 16 million yuan electrical expense could be saved every year only in a small oil field of Jiangsu province in China, while the service lives of beam units, rods, pumps, and tubes could be prolonged, and the period of well without maintenance and the period of wax removal and inhabitation could be prolonged, then technology guarantee could be provided for reasonable development of oil reservoir. As a result the technology to raise the efficiency of machinery system of oil production has a prospect of wide applications. In the end of 1960""s in U.S. a lot of research works were done to this subject, and in 1984 the research achievements had been applied to 1065 wells in California so that the average efficiency of machinery system of oil production had reached 29.4%. In our country in the beginning of 1980"" Daqing oil field began to carry out the research about this problem, and the achievements had been applied to 69 wells in Daqing oil field so that the average efficiency of the machinery system of oil production had reached 28.7%.
In recent years since the research works are continuously deepened and the management is further detailed, the efficiency of machinery of oil production is continuously raised, but these jobs are mainly focused on innovating of the mechanism and lifting efficiency of the pump. An oil production is determined mainly according to API standard and xe2x80x9cPrinciple of oil production technologyxe2x80x9d as a criterion, but these criterions have some weaknesses since they do not mean at minimum of the energy consumption, also do not mean at minimum of mechanism wearing, and only they meet need of the output and requirements of the strength as basic points.
For example the principle of selecting the pump according to xe2x80x9cPrinciple of oil production technologyxe2x80x9d is that, under the condition of meeting the requirement of daily output the pump diameter is selected as smaller as possible based on the selected beam pumping unit, daily liquid output, and pump setting depth, without considering the influences of physical properties of crude oil and borehole deviation. The principle of selecting the pump based on API standard is that, in various pump diameters, the selected pump diameter is what makes the polished rod power minimum when lifting pure water, without considering the influences of physical properties of crude oil and borehole deviation; also in regard to the principle of determining submergence depth, i.e. when gas oil ratio is less than 80 m3/m3, submergence depth is requested at a range of 50 m-200 m. In fact, if the submergence depth is determined according to this request, the efficiency of pump is generally low. The all principles mentioned above could not make a comparison between economic benefits corresponding to using different tube diameters, different steel rod grades, and also could not determine the mechanical oil production cost corresponding to different parameters combinations of machinery system of oil production. The main reason is that, there are no theoretical formula of calculating input power of the machinery system for various dynamic and static parameters in a well producing with a sucker rod, and there is not scientific and reasonable method to select the way of oil production.
Different combinations of production parameters can be used for producing the same daily output in one particular well, however the costs for different parameter combinations are different. Because there is no theoretical formula showing the function relationship between the input power of machinery system of oil production with a rod pump and oil well dynamic and static parameters, when the parameters of the machinery system of oil production are designed for an oil well in which a sucker-rod pump is used, neither oil tube diameter nor steel rod grade can be determined; and no energy consuming and mechanical wearing corresponding to different parameter combinations can be predicted either. It is difficult to define the optimal parameter combination such as tube diameter, steel rod grades, pump diameter, pump setting, rod diameter, stroke, and pumping speed. Not only dependent on liquid production, water cut, gas oil ratio(GOR), and dynamic fluid level, since other physical properties of crude oil, physical properties of oil layer, and borehole deviation of different oil reservoirs, different oil layers, and different oil wells are individually different, these factors will in more or less influence energy consuming and machinery wearing of machinery system of oil production either. Therefore, although well A and B have the same daily liquid production, dynamic fluid level, water cut, and gas oil ratio, there is still a possibility that the efficiency in well A is high but in well B can be very low by using the same parameter combination. As a result there exists neither a mature technology with broad adaptability, nor such oil production method and system with principles of minimum power consumption or optimal comprehensive economic benefits for the same daily liquid production.
Therefore, the object of the present invention is to overcome the shortcoming of the prior art, and to provide a method and a machinery system of oil production with a sucker-rod pump which makes various power losses in oil production significantly reduced and the oil production cost decreased.
the present invention provides a method of oil production with a sucker-rod pump, comprising:
(a) predicting the objective daily liquid production, water cut, and dynamic fluid level of an oil well;
(b) measuring the viscosity of degasified crude oil on the ground and wax precipitation temperature of crude oil;
(c) acquiring physical parameters of the crude oil of the oil well in formation conditions and the parameters of borehole deviation;
(d) measuring the temperature in the middle of the oil zone and the temperature on the surface of the earth;
(e) selecting the type of beam unit;
(f) preliminary determining all ranges of tube diameters, diameters of deep well pump, setting depths of pump, material types of sucker-rod and rod string , strokes of the selected beam unit, pumping speeds of the beam unit;
(g) finding out all of combinations of different pump diameters, pump setting depths, tube diameters, rod material types, rod strings, strokes, and pumping speeds, which can achieve the same daily liquid production in the well, then calculating out input power Pinput of respectively corresponding to each parameter combination according to following formula:
Pinput=Pactivexe2x88x92Pexpansion+xcexa3Ploss
xe2x80x83where:
Pactive is active power (W);
Pexpansion is expansion power (W) caused by crude oil degasifying in tube above the pump standing valve;
xcexa3Ploss is total loss power;
(h) taking the combination of parameters corresponding to minimum Pinput as the system parameters of mechanical oil production, or taking the one corresponding to minimum cost of mechanical oil production as the system parameters of mechanical oil production;
(i) deciding oil tube material type and length based on tube diameter and pump depth, deciding the specification of the deep well pump by pump diameter and maximum stroke of the beam pumping unit, and deciding specification and length of required each type of the sucker-rod by material type and rod string;
(j) deciding the type of the motor coupled with the beam pumping unit by defined pumping speed and system input power so that the oil production system can be established by the special beam pumping unit, the motor, the oil tubes, the sucker-rods, and the deep well pump.
Abovementioned physical parameters of formation crude oil in an oil well include gas oil ratio, saturation pressure, solution coefficient, formation crude oil viscosity, and formation crude oil density.
In order to decide the range of pump setting depth following method can be used: when fluid pressure is larger than or equal to saturation pressure, the pump setting begins from dynamic fluid level, then based on interval step length, sequencing depth is in turn deepened until pump intake pressure is equal to saturation pressure; when fluid pressure is lower than saturation pressure, the pump setting begins from dynamic fluid level, then based on interval step length, sequencing depth is in turn deepened until to top of an oil layer.
The present invention also provides a system of mechanical oil production with a sucker-rod pump, which includes a beam pumping unit, a motor, an oil pumping tube, a kind of sucker-rod combination and a deep well pump; said motor being fitted on the beam pumping unit and driving the latter, the sucker-rod being positioned in said oil pumping tube, said beam pumping unit being connected with the sucker-rod by a jointer, and the sucker-rod being conjoined with the plunger of the deep well pump submerged under the liquid level, the operating cylinder of the deep well pump being connected with said oil pumping tube; wherein structure parameters of individual components in the system are selected as follows: (a) selecting the type of the beam pumping unit based on objective daily liquid production, water content ratio, and dynamic fluid level of the oil well; (b) preliminary determining all ranges of tube diameters, tube length, diameters of the deep well pump, setting depths of the deep well pump, material types of the sucker-rod, rod string, strokes of selected beam unit, and pumping speeds of the beam pumping unit; (c) finding out all of combinations of different pump diameters, pump depths, tube diameters, rod material types, rod string, strokes, and pumping speeds, then calculating out input power Pinput respectively corresponding to each parameter combination according to the formula listed below:
Pinput=Pactivexe2x88x92Pexpansion+xcexa3Ploss
where:
Pactive is active power (W);
Pexpansion is expansion power (W) caused by crude oil degasifying in oil tube above the pump standing valve;
Ploss is total loss power
(d) deciding oil tube specification and length based on tube diameter and pump depth, deciding the specification of the deep well pump based on pump diameter and maximum stroke of the beam pumping unit, and deciding specification and length of required each type of the sucker-rod based on material type and rod string;
(e) taking the parameter combination corresponding to minimum Pinput as the parameters of the machinery of system oil production, or taking the one corresponding to minimum cost of mechanical oil production as the parameters of the machinery system of oil production to be defined;
(f) deciding the type of the motor coupled with the beam pumping unit by defined pumping speed and system input power so that the oil production system can be established by the special beam pumping unit, the motor, the oil tubes, the sucker-rods, the deep well pump.
The system and the method of present invention will be described in detail below with the reference of the accompanying drawing which is schematic view of a machinery system of oil production with a sucker-rod pump.